The acquired immune deficiency syndrome (AIDS) is caused by infection with the human immunodeficiency virus (HIV). Given the neurotropism of the HIV, it is important to develop AIDS therapeutics that are taken up by brain from the circulation. Such drugs must be capable of transport through the brain capillary endothelial wall, which makes up the blood-brain barrier (BBB) in vivo. Until recently, there were few, if any, practical brain drug delivery strategies that allowed for safe delivery through the BBB of therapeutics for the treatment of cerebral AIDS. In the proposed studies, physiologic-based drug delivery strategies will be developed and include chimeric peptides, chimeric antisense oligonucleotides, and cationized antibodies. Chimeric peptides and chimeric oligonucleotides are first coupled to a brain drug transport vector, e.g., a monoclonal antibody to the transferrin receptor, which undergoes receptor-mediated transcytosis through the BBB. Cationized antibodies are formed by chemically raising the isolelectric point of the antibodies to the cationic level as cationic proteins undergo absorptive- mediated transcytosis through the BBB. The model chimeric peptide to be developed in these studies is a novel vasoactive intestinal peptide (VIP) analogue that has been designed specifically for covalent coupling into the transport vector using a disulfide linkage. The VIP analogue has been designed so that it is biologically active following cleavage from the transport vector. A model chimeric antisense oligonucleotide to be studied is a 21-mer antisense oligonucleotide to the tat gene. Both the chimeric peptide and the chimeric oligonucleotide will be coupled to an antitransferrin receptor monoclonal antibody transport vector through an avidin/biotin linkage. These studies will employ the development of avidin fusion proteins, wherein the coupling of avidin to the transport vector (the monoclonal antibody) allows for high efficiency coupling of any biotinylated peptide or oligonucleotide to the transport vector. The model cationized antibody to be studied is directed against a synthetic peptide encoding the sequences that include the active site of the rev protein. Each of the three sets of studies are subdivided into three homologous modules: drug synthesis, drug delivery, and drug action. The drug delivery strategies will be deemed successful if the delivery vehicle can generate in brain concentrations of drugs that are shown to be pharmacologically effective with the drug action studies. The drug action model will include measurements of HIV-1 replication in cultured human peripheral blood lymphocytes.